Conveyor

ABSTRACT

A conveyor system having first second and third stations and a return conveyor in communication with and linking the first and third stations: The first station has a device to selectively feed pallets, one at a time, from the return conveyor to a position underneath an unpackaged work piece disposed on the first station portion of the conveyor system and help position the pallet with the work piece on top of it on to another part of the first station portion of the conveyor system, which conveys the pallet and the work piece to the second station where packaging of the workpiece is carried out, for example, shrinking a plastic sheet about the work piece. Another part of the conveyor system conveys the packaged work piece to the third station where a device removes the pallet from the packaged work piece, places the packaged work piece on another part of the third station portion of the conveyor and places the pallet on the return conveyor for return to the first station.

BACKGROUND OF THE INVENTION Related Applications

This is a division of U.S. Ser. No. 06/936,109, filed Nov. 28, 1986,entitled "Conveyor", now U.S. Pat. No. 4,739,607.

In the furniture industry, it is customary to package a piece ofupholstered furniture (sometimes called a workpiece) by heat shrinking aheat shrinkable sheet of plastic about the workpiece. This is usuallyaccomplished by draping a heat shrinkable plastic over the workpiece andthen conveying the workpiece so draped into an enclosure(a furnace)where hot air (375° F.) is blown against the plastic, causing it toshrink to and take the shape of the outside contour of the workpiece.Usually this process employs a conveyor integral with the furnace. Thisconveyor conveys the plastic draped workpiece into and then out of thefurnace. Most furnaces used for this purpose employ a conveyor at leasta part of which is made up of a plurality of spaced apart memberspositioned transverse to the longitudinal path of conveyor travel. Thespace between the members is required to allow the hot air to enter theenclosure. Hot air comes from the bottom of the furnace (under theconveyor), then into the furnace proper where it comes in contact withthe plastic, causing the plastic to heat shrink about the workpiece.Because of the spaced apart nature of these members, a problem iscreated.

A great deal of furniture, having legs or feet, (sofas, chairs,loveseats for example), is packaged by the heat shrinking method. Thistype of furniture must be first loaded on pallets, then the loadedpallets hand placed on the furnace conveyor. If the pallets were notused, the feet or legs would become lodged in between the transversemembers of the furnace conveyor and cause problems. After the loadedpallet is moved through the furnace and the heat shrinkable plasticpackaging of the workpiece is completed, the packaged workpiece must beconveyed to a position outside of the furnace and removed from thepallet. Additionally, the pallet must be removed from the conveyor andconveyed back to its point of origin for reuse.

The prior art teaches that all of these pallet-workpiece operations areto be carried out by hand. This is inefficient and dangerous. Workmanmust handle the hot, just-packaged workpiece immediately after itemerges from the furnace. Such a practice exposes the workman to burns,not to mention the risk of injury to the packaged workpiece itself.Workmen may also be injured when lifting the packaged workpiece and/orthe pallet. This invention automates all facets of thepreviously-mentioned process, relieving the workman from touching thehot, just-packaged workpiece, lifting and conveying either the packagedworkpiece and/or the pallets.

BRIEF DESCRIPTION OF THE INVENTION

The disclosed inventin is a conveyor system having first, second andthird stations. In addition to these stations there is a return conveyorwhich is in communication with and links the first and third station.The first station has a device that feeds pallets, one at a time, fromthe return conveyor (a first level) to a position underneath anunpackaged workpiece disposed on the first station portion of theconveyor system and raises the pallet to a second level so that theworkpiece is on top of it. Another part of the conveyor system conveysthe pallet from the workpiece to a second station (a furnace) wherepackaging of the work piece takes place. This packaging is accomplishedby heat shrinking a plastic sheet about the workpiece. After packaging,the packaged workpiece is then placed on another part of the conveyorsystem which conveys the packaged workpiece to a third station. At thethird station, there is a device that removes the pallet from thepackaged workpiece, (moves it from the second to the first level),places the packaged workpiece on another part of the third stationportion of the conveyor and places the pallet on the return conveyor(first level) for return to the first station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the first portion of the conveyor systemof the invention.

FIG. 2 is a perspective view of a second portion of the conveyor systemof the invention, FIGS. 1 and 2 being contiguous to one another.

FIGS. 3, 4, and 5 are perspective partial views of the first (loading)station of the invention showing a portion of the first station at itsfirst level (coplaner with return conveyor), second level (coplaner withupstream and downstream conveyor), and third levels respectively.

FIGS. 6, 7, 8, 9, 10 and 11 are pictorial perspective views of themanner the apparatus of FIG. 1 (first station) may be used to position,raise, dress, turn (rotate) and lower a workpiece prior to packagingsame.

FIGS. 12 and 13 are partial side elevations of third station unloadingapparatus.

FIG. 14 is a perspective partially cut-a-way side view of the apparatusof the third (unloading) station of the conveyor system.

FIGS. 15 and 16 are perspective partially cut-a-way views of theapparatus of the first (loading) station of the conveyor showing thetransfer of a pallet from the return conveyor (second level) to thefirst station of the conveyor system while a portion of the conveyorsystem at the first station is at the second level.

FIGS. 17 and 18 are partial cut-a-way perspective views of the apparatusof the third (unloading) station showing removal of a pallet from aportion of the conveyor system while it is at the second level to thereturn conveyor.

FIGS. 19 and 20 are a partial plan view of a two switchstriker platetransfer arm arrangement employed at the first and third stations.

FIG. 21 is a perspective partial view of the powering apparatus used torotate rollers 16 of return conveyor 3.

DETAILED DESCRIPTION OF THE INVENTION

A general understanding of the entire conveyor system can be achieved byviewing FIGS. 1 and 2. FIG. 1 is a generalized prospective view of allof the first station and part of the second station of the invention.FIG. 2 is a generalized perspective view of a part of the second and allof the third station of the invention. FIGS. 1 and 2 when viewed in acontinuous manner, present a general description of the invention inpictorial form.

Element 1 of FIG. 1 represents the first station and element 2 of FIG. 1identifies the second station of the invention. Element 4 of FIG. 2represents the third station of the invention. All of these are disposedgenerally at a second level. Portions of elements 1 and 4 are adapted tobe moved to other levels as will be later described. It will be notedthat the entire invention is a conveyor system comprising elements 1, 2,3, and 4. Element 3 of FIGS. 1 and 2 is disposed at a first level and isa return conveyor, linking and communicating with the first and thirdstation. The first level is lower than the second level, the secondlevel represented by the position of frame 26 of FIG. 4. The primarypurpose of return conveyor 3 is to return pallets 6 from station 4 to aposition just out by, but not under, station 1. Rollers 16 of returnconveyor 3 (first level) are coplaner with rollers 22 of frame 23 whenframes 23 and 26 are in position shown by FIG. 3. Station 1 is aconveyor made up of legs 8 on which frame 7 is attached. Disposed onframe 7 is a continuous belt type conveyor 14 (well known in the priorart) that terminates at a point denoted by element 38 and is at thesecond level.

That portion of station 1 delimited by and in between point 38 and apoint denoted by element 39 contains a device for disposing pallets 6underneath workpieces 13 over which heat shrinkable plastic 12 has beendraped. Pallet 6--disposed on return conveyor 3 (more particularlyrollers 16) in a manner that will be hereinafter described in moredetail--is moved from return conveyor 3 by arms 20 onto rollers 22 (seeFIG. 3), while such rollers are in the first level position as shown inFIG. 3. A workman 42 then operates means 78 (an on-off switch) to stopthe conveyor system and if necessary hand positions the plastic drapedworkpiece (elements 12 and 13) over frames 23 and 26. See FIGS. 6 and 7.After positioning the workpiece, the forward most position of pedal 46(an on-off switch) is depressed causing frames 23 and 26 to be driven bya lifter (a hydraulic and a gear system) from level two to level onewhere they are now ready to be loaded with a pallet 6. When frames 23and 26 reach level one they stop but with power still on them, biasingthem downward. When frame 23 reaches level one it strikes time delayswitch 65, which causes gate members 20 to extend removing a singlepallet from return conveyor 3 and placing it on frame 23. Striker plate114 strikes on-off switch 104 (FIGS. 19 and 20) when so extended,causing arm 20 to retract.

Retraction of gate member 20 causes striker plate 114 to activateanother time delay switch 60 that causes stop member 98 (see FIG. 16) tobe depressed a predetermined length of time so as to allow anotherpallet 6 to be moved upstream on conveyor 3 to a position alongsideframes 23 and 26, ready for the next reload. Stop member 98 then goes toits upright position shown in FIG. 16, presenting further movement ofpallets 6 toward station one. Rollers 16 are continuously powered asshown in FIG. 21. Subsequently, the rearward most terminal position ofpedal 46 is depressed causing the first mentioned hydraulic system to bedriven in a reverse direction to raise frames 23 and 26 from level oneto level two. A more detailed description of station one apparatus tocarry out this pallet transfer will be explained later.

If the heat shrinkable plastic 12 draped over workpiece 13 needs nofurther "dressing up", the workpiece and pallet combination is thenmoved on to conveyor 5 by a station one workman 42. Usually the terminalportions of the heat shrinkable but not yet heat shrunk plastic 12 needsto be "dressed up," i.e. tacked or otherwise affixed to the bottomportion of the workpiece 13. In this event, the workpiece draped withthe heat shrinkable plastic needs to be raised to a third level so thatthe workman can accomplish this task. See FIGS. 9 and 10.

Shown in FIG. 5 is frame 23 and rollers 22 in their raised position: atthe third level. This third level is higher than the previouslyidentified first and second levels and makes it easy for a workman witha stapling gun to tack or affix the terminal portions of yet-to-beshrunk heat shrinkable plastic 12 to the underside of workpiece 13.After this operation is completed, pedal 45 is actuated and frame 23 androllers 22, along with its pallet 6, workpiece 13, and heat shrinkableplastic 12 disposed thereover is lowered again to that position as shownin FIG. 4 where rollers 22 and 35 are coplaner: the second level. Thenpallet 6, workpiece 13 and heat shrinkable plastic 12 is rolled ontoconveyor 5 to begin its journey through furnace 17. The procedure justdescribed is shown in FIGS. 6, 7, 8 and 9. Note workman 42 and staplinggun 47. When one end of two way pedal 45 is depressed a hydraulic device(not shown) is activated that raises cylinder 24, frame 23, pallet 6 andits load (elements 12 and 13) from the second to the third level. SeeFIG. 8.

Shown in FIG. 9 is a third pedal 78 connected to a power source (notshown) for driving conveyor belt 14. By moving pedal 78, conveyor belt14 is activated until a plastic 12 draped workpiece 13 on pallet 6 ispositioned over opening 21 ready to receive pallet 6 on its under side.Then it is manually deactivated. Then pallet 6 and workpiece 13 is thenraised up to a third level by activating pedal 45 and the proceduresshown in FIGS. 9 and 10 respectively are carried out. Afterwards, thedraped workpiece is lowered from level three to level two by manuallyactivating pedal 45 (see FIG. 11). Afterwards, pedal 78 is manuallyactivated, causing conveyor 14 to move until another plastic 12 drapedworkpiece 13 is likewise positioned over opening 21.

Pushing pedal 45 on its forward terminal position sends frame 23 fromits second to a third (higher than the second) level. Pushing pedal 45on its rearward terminal position sends frame 23 from its third to itssecond level. Pushing downward on pedal 78 starts the conveyor system. Areverse motion stops the conveyor system.

Conveyor 14 (a prior art conveyor) is disposed between lateral framemembers 7 and terminates at a point identified by element 38. Conveyor14 drives draped workpiece 13 onto guide members 9 positioned on bothlateral sides of opening 21. Disposed inside of opening 21 is frame 26into which frame 23 is removably received. On the terminal portions offrame 26 are tabs 38 (FIG. 4), affixed to chain 29 by means of fasteningmeans 39. Chain 29 is threaded over sprockets 27 and 28 and driven by apower means (not shown). Sprockets 27 are affixed to axles 28, which isjournaled in bearings 36. A workman can activate a hydraulic power, gearmeans (see for example, elements 67, 68, 69 and 71 of FIG. 3 whichoperate in the same manner as elements 100, 71, 70, 69, 67 of FIG. 14)via pedal 46 to drive axle 28 to cause frame 26 (along with frame 23 androllers 22 therein) to be moved from that position (second level) shownin FIG. 14 (rollers 22 coplaner with rollers 10) to that position (firstlevel) shown in FIG. 3 (rollers 22 coplaner with rollers 16). Once frame23 is driven to level one, transfer arms 20 are activated to move apallet 6 onto frames 23 and 26. Subsequently, frames 23 and 26 arereturned to level two. Assuming that some "dressing" needs to be done tothe bottom terminal portions of heat shrinkable, but not yet shrunkplastic 12, an operator can activate pedal 45 to cause cylinder 24 toextend frame 23 and rollers 22 to the upward position (third level) asshown in FIGS. 5, 9, and 10. Activation of pedal 45 lowers cylinder 24from that position (third level) shown in FIGS. 5, 9 and 10 to thatposition shown in FIG. 4 (second level) where rollers 22 are coplanerwith rollers 10 and 35.

Referring to FIGS. 3 and 4, the lifter shown in these figures thatperforms the function of moving frames 23 and 26 from level one to leveltwo and from level two to level one is constructed of a frame 34 towhich journal bearings 36 are affixed. Axle 28 is journaled in bearings36 and affixed to sprocket 27. Chain 29 is threadedover sprockets 27 andis affixed to frame 26 by means of tab 38 and fastening means 39. Frame26 is made of angle iron thereby allowing frame 23 to be removablyreceived therein. The movement of frame 26 from a first (FIG. 3) to asecond (FIG. 4) level also moves frame 23 (and rollers 22 affixedthereto) in a like manner. Sprockets 27 and axles 28 are rotated by rackand pinion gear element at station one--see elements 67 and 68 of FIG.3, remembering that they operate like elements 67 and 68 of FIG. 14--theoperation of which is explained later in connection with the descriptionof the third station.

Cross members 25 are affixed to the bottom portion of frame 26 byupstanding members 111. Cylinder member 24, powered by a prior arthydraulic means (not shown), is coaxially received inside of cylinder40, both of which are received in aperture 37 of frame 34 and is used tomove frame 23 from the second to the third and from the third to thesecond level. Because cross members 25 are also affixed to frame 26 theyprovide a means for moving tube 40 from that position shown in FIG. 5 tothat position shown in FIGS. 3 and 4.

Rollers 10 (see FIGS. 3, 4, and 5) are not powered and are journaled inlateral terminal portions of frame member 9. These rollers facilitatethe movement of workpiece 13 onto conveyor 5. Conveyor 5 is disposed onframe 7 supported by legs 8 and is part of the second station 2.

Station 2 is known prior art; thus, no detailed description of itsstructure will be made. In essence, it consists of a furnace 17, ingressand egress conveyors 5, a source of hot air (not shown) and a spent airexhaust system 30. There is another conveyor (not shown) inside of thefurnace housing 17 composed of a plurality of slats (not shown) disposedtransverse to the directional arrows shown in FIGS. 1 and 2. These slatsare spaced apart and are basically tubes that have a rectangular crosssection. The spaced apart nature of the slats or tubes is a requirementso that hot air may be forced into the furnace 17, such being doneunderneath the tubes and workpiece 13 with its plastic covering 12. Theentering hot air is approximately 375° F. When the draped workpiececomes in contact with this hot air, the heat shrinkable plastic 12shrinks over and conforms to the outside contours of workpiece 13. Theemerging packaged workpiece 11 is transported from conveyor 5 ontospaced apart conveyors 41 delimiting open space 42. Packaged workpiece11 then travels in the direction of the directional arrow (unnumbered)until it hits a limit switch 50 (FIG. 14), thereby stopping the motionof conveyors 41. At this time pallets 6 are removed from underneath thepackaged workpiece and disposed, by means of arms 20, onto returnconveyor 3 to be transported back to the first station 1. Details ofthese steps and apparatus to achieve same will be described later.

Return conveyor 3 is a conveyor comprising roller members 16, rotativelyjournaled in spaced apart frame members 15, positioned at a first leveland is affixed to the first station 7 by means of cross members 44.Roller members 16 are powered (continuously) by that apparatus shown inFIG. 21, so as to return pallets 6 from the third station 4 to the firststation 1. Rollers 16 have axles 112 affixed to sprockets 11 which arethreaded over drive chains 109, one of which is threaded over sprocket108 affixed to axle 107 of gear 106. Motor 105 drives gear 160 and thusrollers 16.

After pallet 6 is removed from the packaged workpiece 11, packagedworkpiece 11 is then transported by spaced apart conveyor belts 41 ontoconveyor 33 and thence to storage or other disposition.

Element 4 of FIG. 2 denotes the third station, similar in structure andoperation to the structure and operation of the first station. Acomparison of FIGS. 1 and 2 shows this similarity. Spaced-apart conveyorbelts 41 disposed on rollers 59 form opening 42 somewhat similar toopening 21 of element 1. Disposed in opening 42 is frame 57. Removablyreceived inside frame 57 is frame 52. Rollers 51 are rotatively attachedto frame 52. Frame 57 (along with its attached rollers 48) is adapted tobe moved from that position shown in FIG. 12 to that position shown inFIG. 13 and the reverse. Non-powered upstanding rollers 48 affixed toelement 57 are adapted to be rotated around their vertical axis. Thereare two spaced apart rows of rollers 48 disposed along the longitudinalaxis of frame 57, adapted to fit inside of that space delimited byaperture 58 of pallet 6. Pallet 6 is discharged from conveyor 5 (seeFIG. 2) onto conveyor belts 41 and does so with frame 57 in the positionshown in FIG. 12, its normal position. Rollers 48 are adapted to be"threaded" inside of pallet aperture 58 and in rolling contact with theunder side of pallet 6 to position it on rollers 51 in a predeterminedposition so that pallet 6 can be subsequently removed from the packagedwork piece 11 and disposed on return conveyor 3 as shown in FIG. 2. Thisremovable function will be more fully described at a later time.

There are times, however, when a pallet with an aperture 58 is notdesirable and only a box or solid pallet 56 is desired. In this case,pallet 56 strikes goose neck arm 43 which in turn activates time delayswitch 55 like that disclosed in U.S. Pat. No. 4,553,999. Time delayswitch 55 then activates a lifter (hydraulic cylinders 110) causingframe 52 to move from that position shown in FIG. 12 to that positionshown in FIG. 13 and dwell in the last mentioned position for apredetermining length of time. After expiration of this predeterminedtime (preset in switch 55), hydraulic cylinders 110 move frame 57 fromthat position shown in FIG. 13 to that position shown in FIG. 12. Thepredetermined length of time is that amount of time it would take box 56to clear all of the rollers 48, i.e., its trailing extreme left freeedge clears the most rightward roller 48 of FIGS. 12 or 13. In such acase, box or pallet 56 rolls on rollers 51 from that position shown inFIG. 13 to the right and onto the rightward terminal portion of conveyorbelt 41 as shown by the most rightward element 11 of FIG. 2.

In the event that pallets 6 with aperture 58 are used, goose neck arm 43then passes through aperture 58 untouched and time delay switch 55 isnot activated. After passing over (and not activating) goose neck arm43, pallet 6 comes in contact with and activates limit "on-off" typeswitch 50. Limit switch 50, when activated, stops conveyor belts 41 andactivates a power means (not shown). This power means moves anotherlifter that causes sprockets 53 and 75 to rotate in a given directionlowering frame 52 and pallet 6 from its second level to its first levelso that rollers 51 are coplaner with rollers 16 of return conveyor 3.This lifter is a hydraulic system and a gear system. It will be notedthat chains 54 are threaded over sprockets 53 and are attached to frame52 by means of tabs 38. Frame 52 remains at this first level untilpallet 6 is removed from rollers 51 by arms 20 and deposited on rollers16 of return conveyor 3. Such removal causes limit switch 50 to returnto its normally "off" position, as shown in FIG. 14.

Transfer arms 20 at the third station pivot about upright members 31journaled in frame 79 and performs two functions: (a) pushes pallet 6from rollers 51 onto rollers 16 while both are coplaner with one another(at the first level) and (b) activates time delay switch 60 by strikerplate 114 on arm 20. Throughout this specification the term time delayswitch means a switch as described in U.S. Pat. No. 4,553,999, thecontents of which are incorporated herein by reference as if it werefaithfully reproduced therein. Time delay switch 60 is so "timed" thatafter activation and it "times out" it causes the lifter (the hydrauliccylinder and a gear system) to drive frame 52 from the first level tothe second level, i.e., to that level shown in FIG. 14. At this level,tension on belt 64 is restored (power is removed when frame 52 and 57are lowered from level two to level one) to rollers 51, and the conveyorsystem is ready for another workpiece.

When switch 50 (an on-off switch) is activated it activates the fluid incylinder 71 that drives piston rod 70 that drives rightwardly rack gear67 that rotates pinion gear 68 that drives sprocket 75 that drives chain74 that, in turn, drives frames 52 and 57 from level two to level one,that position where rollers 51 are coplaner with rollers 16 of returnconveyor 3. Piston arm 70 is attached to a fastening device 69 which isfastened to rack gear 67. Pinion gear 68 is in mesh relationship withrack gear 67 and is also affixed to axle 72, the terminal portions ofwhich are journaled in upstanding members 73.

Switch 50 is an on-off switch. Pallet 6 activates switch 50, whichactivates a power means (not shown), that drives the fluid in cylinder71. Such power is continuously applied until pallet 6 is removed at thefirst level. After pallet 6 is removed, switch 50 moves to its normallyoff position shown in FIG. 13. After rack gear 67 has reached the limitof its rightward travel (rollers 51 will be at the first level, coplanerwith rollers 16) second transfer arms 20 (there are first transfer arms20 at the first station) are activated to remove pallet 6 from rollers51 to roller 16. When frames 57 and 52 are lowered to the first levelthey strike arm 66 of time delay switch 65. As soon as frames 52 and 57begin their descent, the tension in belt 64 is reduced removing drivepower from rollers 51. Drive power comes from motor 60, pulley 76, belt64, pulleys 102 and belt 101. Belt 64 is attached to motor 60 throughpulley 76 and is further threaded so as to power rollers 51. See element102 (roller) and 101 (drive belt). Note stop means 77 which acts as ameans to stop pallet 6, notwithstanding the power on rollers 51 prior tomoving tension from 64 to cease rotation of same.

After time delay switch 65 of the third station is activated, a powermeans (not shown) attached to hydraulic cylinder 19 (FIGS. 17 and 18) isenergized. Hydraulic cylinder 19 is connected to two second transferarms 20 comprising two gates. Activation of switch 65 causes rod 92 ofhydraulic cylinder 19 to extend and retract to move second transfer arms20 from a retracted first (see FIG. 12) to an extended second (See FIG.18) position. Extension of arm 20 causes striker plate 114 to activateswitch 104 resulting in the reverse, i.e., movement of second transferarms 20 from their extended second to their retracted first position.After retraction, time delay switch 60 is activated causing a signal tobe sent to the power means of cylinder 71. At this state, rod 70 is inits most extended position with rack 52 and 57 at the first level. Areverse operation takes place, i.e., cylinder 71 cause rod 70 to move tothe left (retracts) thereby raising frames 52 and 57 to the second levelwhere rollers 51 are coplaner with roller 16, as shown in FIG. 24.

There is a critical relationship between on-off switch 50 and time delayswitch 60 and 65. Only after switch 50 is deactivated (in its offposition) will time delay switch 65 respond to one of its intendedfunctions, i.e., driving piston rod 70 to the left to lift frames 52 and57 from the first to second level. This is necessary because frames 52and 57 (like frames 23 and 26) must be held down (maintained at thefirst level) until second transfer arms 20 clear pallet 6 from rollers51 to rollers 16 of return conveyor 3. Otherwise havoc would result. Theact of clearing pallet 6 causes switch 50 to return to its normal offposition. After switch 50 is returned to its off position (while frames52 and 57 are at the first level) time delay switch 60 then begins itstimed activation of hydraulic cylinder 71 and its associated gear systemto raise frames 52 and 57 from the first to the second level. See FIG.14.

Reference is now made to FIGS. 15 and 16, which depict the firsttransfer arms (at the first station) in their first (retracted) andsecond (extended) positions respectively. Upright member 94 is attachedto frame 79 and to support block 93. Yoke 91 is rotatively attached bypin 91 to support bock 93 and forms an integral part of hydrauliccylinder 19. Hydraulic cylinder 19 has a piston rod 92 attached to yoke90. Yoke 90 is pivotally attached by pin 97 to arm 89. Arm 89 is fixedlyattached to upright gate member 31. Upright gate member 31 and arms 20comprise the main components of the first transfer arm. Upright gatemembers 31 are rotatively journaled into plates 81 and 88 so thatelement 31 may rotate about their vertical axis. Hydraulic cylinder 19is activated by time delay switch 65 in response to frames 52 and 57being at the first level, causing piston rod 91 to extend from thatretracted first position shown in FIG. 15 to that extended secondposition shown in FIG. 16. Retraction of piston rod 92 from thatposition shown in FIG. 16 to that position shown in FIG. 15 causes thefirst transfer arms to be moved from its extended (pallet 6 removal)position of FIG. 16 to that retracted position shown in FIG. 15.Extension and retraction of piston rod 92 causes the right hand positionof first transfer arms 20 to extend and retract. Such activation is inresponse to and takes place after a workman releases pedal 78 (stoppingthe conveyor) then activating pedal 46 to send frames 23 and 26 fromtheir second level (FIG. 4) to their first level (FIG. 3) thuscontacting and activating time delay switch 65. Lowering of these framesis achieved by means of a hydraulic cylinder 71 and rack 67 and piniongear 68 axle 72 and sprocket 68 like that of FIG. 14. The structure andoperation of such apparatus has already been shown in connection withelements 100, 71, 70, 69 and 67. Like elements are shown in FIG. 3. Forthe sake of simplicity, they are not shown in any other Figures relatingto station one, but it is to be understood that their presence isnecessary at the first station for the operation of the loadingapparatus. Frame 23 strikes and activates time delay switch 65. Switch65 in turn activates a power source (not shown) that activates the fluidin hydraulic cylinder 19.

The right hand portion of first transfer arm 20 at the first station isconnected to the left hand portion by means of linkages 86, slot 87, pin85, arm 83 movably attached to arm 84, arm 84 movably attached to arm93, arm 93 movably attached by means of slot 96 and pin 95 to arm 82,and arm 82 rotatively attached to arm 20. Thus, through the previouslydescribed linkage, movement of the right hand portion of arm 20, theleft hand portion of first transfer arm 20 is also moved from thatposition shown in FIG. 15 to that position shown in FIG. 16. At thisposition, switch 104 is activated by striker plate 114, the power means(not shown) is reversed and piston rod 92 is retracted from thatposition shown in FIG. 16 to that position shown in FIG. 15. A viewingof FIGS. 15 and 16 shows the transfer of a pallet 6 at the first stationfrom return conveyor 3 to frame 23, while frame 23 is at the firstlevel. When arms 20 of first transfer arm are retracted time delayswitch 60 is activated operating stop member 98.

Reference is made to FIGS. 19 and 20 for an understanding of theoperation and apparatus of the transfer arms 20 at both the first andthird stations. Operation of these elements at the first station will beexplained first. After time delay switch 65 is activated, arms 20 gofrom retracted to their extended position. Striker plate 114 on arm 20and upright member 31 contacts on-off switch 104 and activates it,sending arms 20 back to their retracted position. In the retractedposition, striker plate 114 contacts time delay switch 60, whichoperates stop member 98, i.e., causes it to retract for a predeterminedlength of time, enough to allow a single pallet to be fed alongsidewhere frame 23 would be if it were at the first level. After this lengthof time, time delay switch 60 times out causing stop member 98 to returnto its upright (pallet blocking) position as shown in FIG. 16.

In the case of the third station, the operation of the above identifiedelements is the same, except that time delay switch 60 operateshydraulic cylinder gear system lifter of the third station to raiseframe 52 and 57 from the first to the second station. On the other hand,at the first station, depression of pedal 46 operates hydraulic cylinder71 rack 67 and pinion gear 68, axle 28, sprocket 27 and chain 29, toraise frame 23 from its first (FIG. 3) to its second (FIG. 4) level, aspreviously described.

Element 82 is a frame member used to delimit guard member 18. Crossmembers 44 bridge the gap between return conveyor 3 and rack 23 andtheir upright free edges 113 slope upwardly from left to right formingan upstanding lip in combination with rollers 22 and frame 23. Crossmembers 44 are "spring loaded" (not shown) so that they will depresswhen loaded with pallet 6 to the extent that free edge 113 will be flushwith the upper most free edge of element 34. Once a pallet 6 is pushedover this lip, it cannot reverse its direction and cause harm totransfer arms 20. Elements 99 are rollers rotatively affixed toupstanding members 20 and provide a rolling surface between transferarms 20 and pallet 6.

What has been explained in the previous paragraphs is the operation offrame 23 and transfer arms 20 at the first station, to move a pallet 6from the return conveyor 3 onto frame 23 of the first station when frame23 is at the first level as shown by FIG. 3. Also explained above is themechanism and procedure by which the pallet is then raised from levelone to level two where pallet 6 comes in contact with the underside of aworkpiece 13 yet to be packaged. There yet remains further explanationregarding pallet movement by transfer arms at the third station i.e.,the unloading station. For this explanation, reference is made to FIGS.17, 18, 19 and 20 plus the description above.

The apparatus shown in FIGS. 17 and 18 should be viewed in combinationwith and added to the apparatus shown in FIG. 14. FIG. 17 is FIG. 14viewed from the opposite side of FIG. 14. Three hydraulic systems arepresent at the third station, i.e., the hydraulic systems of FIGS. 14and 17 (elements 71 and 14) and hydraulic member 110 of FIGS. 12 and 13.Element 71 raises and lowers frame 52. Element 19 operates transfer arms20. Element 110 raises and lowers frames 52 and 57. The operation of thefirst of these hydraulic systems (elements 67, 68, 69 and 71) havealready been explained. The other hydraulic system operates rod 92 andconsists of hydraulic cyinder 19 rotatively affixed to frame 73 by meansof block 103 and pin 91. Hydraulic cylinder 19 has a piston rod 92 andyoke 90, rotatively connected to linkage 89 by pin 97. Linkage 89 isaffixably attached to upstanding member 31, which will be remembered isrotatively journaled in base member 79. There are two upstanding members31, as was in the previously-described case for FIG. 16, both affixed totransfer arms 20. On the terminal portions of the transfer arms 20 areroller means 99, adapted to roll against an outermost surface of pallet6. Hydraulic cylinder 19 and its associated linkage (previouslyidentified) operate in the same manner as like numbered elements shownand previously described in FIG. 16. Additional linkages in associationwith the transfer arm 20 of FIG. 17 are those linkages identified aselements 84, 93, and 82. Note also linkage member 86. These also work inthe same manner as for like numbered elements as described for FIG. 16and it is believed that no further description is needed in view of theprevious discussion of these parts.

There are two "gates" at stations one and three, each powered by anhydraulic system and each having an upstanding member 31 about whichtransfer arms 20 pivot. Transfer arms 20, at both the first and thirdstations, form the operative portion of the "gates", for pushing apallet from a frame to the return conveyor (third station) or from thereturn conveyor to a frame (first station) as the use may be. Anadditional hydraulic system at each station is used to lower a frame,from a second to a first level and to raise the frame from the first tothe second level, each such hydraulic system employing an associatedrack and pinion gear arrangement as shown in FIGS. 3, 14 and 18. Eachhydraulic and gear system operate to raise a frame from level one tolevel two after the transfer arms have worked their process. At stationone, raising and lowering of frame 23 is in response to activation of anon-off switch. At station three, frame 52 is only lowered in response toactivation of an on-off switch. Stations one and three each have a timedelay switch that is activated by the presence of the respective stationframe (23 and 52) being at the first level. When activated, a hydraulicsystem is powered and extends the station's two gates which activatesanother switch which retracts the two gates. The respective gates intheir retracted position activate still another time delay switch thatcauses the station's hydraulic rack and pinion gear system to reverse,raising either frame 23 or 52 from level one to level two.

What is claimed is:
 1. A method of packaging a workpiece comprising:(a) providing a workpiece, a pallet with an uppermost and lowermost surfaces, a conveyor system, and a return conveyor, the conveyor system having a first, second and third stations at a first level and the return conveyor, communicating with the first and third stations for returning pallets from the third to the first station, disposed below at a second level and laterally offset from said conveyor system; (b) placing the workpiece on the conveyor system and conveying the workpiece to the first station; (c) conveying the pallet laterally from the return conveyor to a position below the workpiece; (d) moving the pallet vertically to the first level so that it's uppermost surface is in contact with the workpiece and its lowermost surface is in line with the conveyor system; (e) conveying the pallet and workpiece thereon to the second station and packaging the workpiece to create a packaged workpiece; and, (f) conveying the packaged workpiece and pallet on the conveyor system to the third station and at such station vertically lowering the pallet from the packaged workpiece and then laterally moving it onto the return conveyor and placing the packaged workpiece on the conveyor system.
 2. The method of claim 1 including the further step of conveying the package workpiece from the third station to a predetermined place.
 3. The method of claim 1 including the further step of conveying the pallet from the third to the first station on the return conveyor.
 4. The method of claim 1 including the step of raising the pallet and workpiece while both are at the first station to a predetermined height above the conveyor system prior to carrying out the step described in subparagraph (e).
 5. The method of claim 4 including the step of lowering the pallet and workpiece from said predetermined height prior to carrying out the step described in subparagraph (e).
 6. The method of claim 1 wherein steps (c) and (d) comprise the steps of:(a) providing a moveable first frame in line with said conveyor system as a part of the first station; (b) lowering the moveable frame from the first to the second level; (c) laterally removing the pallet from the return conveyor and placing it on the moveable frame; and, (d) vertically raising the moveable frame from the second to the first level and in contact with the workpiece so that the work piece rests on the uppermost surface of the pallet.
 7. The method of claim 1 wherein removing the pallet from the packaged workpiece at the third station comprises the steps of:(a) providing a second moveable frame in line with said conveyor system as a part of the third station; (b) placing the pallet with the packaged workpiece disposed on it on the moveable frame; (c) vertically lowering the moveable frame and pallet from the first to the second level; and, (d) laterally moving the pallet from the moveable frame to the return conveyor.
 8. The method of claim 7 wherein coincident with step (c) of claim 7, the packaged workpiece is disposed on said conveyor system.
 9. The method of claim 7 wherein the second moveable frame is provided with at least one upstanding roller and the pallet is guided to a predetermined position on the frame at the third station prior to lowering said frame by said upstanding roller.
 10. The method of claim 7 wherein the pallet has an aperture in its underside into which the upstanding roller is removably received. 